Cooperative behavior of Zn cations in Bi-based perovskites: A comparison of (Bi,Sr)2ZnNbO6 and (Bi,Sr)2MgNbO6

Shigeyuki Takagi, Valentino R. Cooper, David J. Singh

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7 Citations (Scopus)


We investigated the polar behavior of the double perovskite (Bi,Sr) 2MgNbO6 using first-principles density-functional theory calculations. We find that the magnitude (75 μC/cm2) and direction (along [111]) of the polarization are comparable to our previous results for the A-site size difference (Bi,Sr)2ZnNbO6 and (Bi,Pb) 2ZnNbO6 systems. However, comparisons with the (Bi,Sr)2ZnNbO6 compound indicate that the presence of Zn modestly enhances the off-centering of the Sr and Nb cations as well as the Born effective charges of both Bi and Nb. Analogous to the corresponding Pb-based perovskites, Pb(Mg1/3Nb2/3)O3 and Pb(Zn 1/3Nb2/3)O3, we demonstrate that the differences in the experimentally observed critical temperatures are related to the differences in polarization between the two materials. A local dipole analysis indicates that the most significant contribution arises from the enhanced cooperative couplings with the larger Zn displacements.

Original languageEnglish
Article number115130
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number11
Publication statusPublished - 2011 Mar 21


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